TOKYO, May 26 (Reuters) - A global aluminium producer has offered Japanese buyers a premium of $480 per metric ton for July-September primary metal shipments, up 36%-37% from the current quarter, three sources directly involved in quarterly pricing talks said on Tuesday.

Japan is Asia's major importer of the metal and the premiums for primary metal shipments it agrees to pay each quarter over the London Metal Exchange (LME) cash price CMAL0 set the benchmark for the region.

For the April-June quarter, Japanese buyers agreed to pay a premium of $350-$353 per ton PREM-ALUM-JP, up 79%-81% from the prior quarter and the highest in 11 years, as the Middle East war tightened supply.